1. Technical Field
The present invention relates to a position measurement device and method. Specifically, the present invention relates to a position measurement device and method for measuring the coordinates of a photographing device or a photographed object by keeping track of a dynamic image of the object when the photographing device moves relative to the object.
2. Related Art
There is known a technique to measure the position of a photographing device by continuously photographing a photographed object while the photographing device is moving relative to the object. When the photographing device is actually mounted on a moving body such as a car to perform photographing, however, the acquired images may occasionally be far from stable and require vertical or rotational corrections frame by frame, due to the sway of the car. In some cases, moving objects such as another car, a bird flying or a leaf falling, for example, may intervene between the photographing device and the object, causing feature points to be hidden behind and restored again. Thus, there is a need to process the sway of such a photographing device and feature points that disappear and reappear. On other hand, for the case where a stationary object is photographed with a stationary photographing device, there is disclosed a 3D measurement technique to precisely and automatically search for corresponding points for measurement. (See Patent Document 1)
[Patent Document 1] Japanese Patent Application No. 2002-64094 (paragraphs [0018] to [0073], FIGS. 1 to 11, etc.)
Thus, it is required to provide a technique that can precisely measure the photographing position and posture of a photographing device or the coordinates of an object to be photographed from moving images or photographed images that sequentially change gradually or little by little, even in the case with the need to process the sway of the photographing device and the disappearance and reappearance of feature points, by developing and applying the technique to photograph a stationary object to be photographed with a stationary photographing device described above to the case where either one of them is mobile.
The object of the invention is to provide a technique that makes it possible to measure with good accuracy the position and posture of a photographing device, or coordinates of a photographed object, from an animated or moving image or from a photographed image changing little by little.